An Apparent SporadicEndolymphatic Sac Tumor in a14-Year-Old Boy

Endolymphatic sac tumors (ELSTs) are rare, low-grade, histologically benign tumors arising from the epithelial lining of the endolymphatic duct or sac. They are slow growing but locally invasive and can be associated with von Hippel-Lindau disease. While there are cases in the medical literature documenting this type of tumor in adults, reports of ELSTs in the pediatric population are limited. The authors report the fifth reported case of a pediatric ELST in the English literature. A 14-year-old Jehovah’s Witness presented with a progressive two-year history of right-sided hearing loss, balance problems, gait difficulty, and bleeding behind the right tympanic membrane. Computed topography (CT) and magnetic resonance imaging (MRI) of the brain and temporal bone revealed a large lesion eroding into the petrous and mastoid bones with extension abutting the brain stem and invading the right transverse sinus. Due to the size and hypervascularity of the tumor, as well as the refusal of the patient and family to receive possible intra-operative blood transfusion, pre-operative tumor embolization and staged surgical resection were used for excision. Histopathological staining and electron microscopy confirmed the diagnosis of ELST. Immediate post-operative imaging did not reveal any residual tumor. Post-operative examination revealed persistence of the right-sided hearing loss that was present pre-operatively. A new facial nerve paralysis was noted post-operatively and remained unchanged at 21 months post-resection follow-up. MRI imaging at 21 months follow-up revealed recurrent tumor. The imaging workup for von Hippel-Lindau disease has been negative. We conclude that it is possible to have reasonable functional outcomes for children with ELSTs using staged resection techniques, though such approaches do not preclude delayed recurrence.